1. Field of the Invention
The present invention relates to a substrate transfer apparatus and a method of driving the same, and more particularly, to a substrate transfer apparatus and a method of driving the same capable of moving a plurality of guide rails and adjusting a gap therebetween using a single ball screw shaft.
2. Description of the Related Art
A known apparatus for mounting components on a printed circuit board includes a base frame, an X-Y gantry, a component suction device, a substrate transfer device, a component supply device, and so on. The X-Y gantry is assembled on the base frame to move the component suction device in X and Y axis directions.
The component suction device is disposed on the X-Y gantry and is thereby moved to mount components supplied through the component supply device on the printed circuit board. The printed circuit board, on which the components are mounted, is transferred to a component mounting position by the substrate transfer device.
Hereinafter, a conventional substrate transfer apparatus 10 will be described in detail with reference to FIGS. 1 and 2.
The substrate transfer apparatus 10 includes a pair of guide blocks 20, a first ball screw shaft 30, a second ball screw shaft 40, a first drive unit 34, a second drive unit 44, and a base frame 52.
The guide blocks 20 include a first guide block 21 and a second guide block 22. Each of the guide blocks 20 includes a guide rail support frame 23 and a guide rail 24. The guide rail 24 is mounted on the guide rail support frame 23. A conveyor belt 26, on which one side of a printed circuit board 28 is seated, is disposed on an upper surface of the guide rail 24. The conveyor belt 26 may be driven by a roller (not shown) disposed on the guide rail 24.
The first ball screw shaft 30 passes through the guide rail support frame 23 and is rotated by the first drive unit 34. The first drive unit 34 is fixed to a guide rail support frame 23a of the first guide block 21 by a bracket 35, and connected to one end of the first ball screw shaft 30 to be driven by a motor.
A first ball screw nut 32 may be installed at a through-hole (not shown) of a guide rail support frame 23b connected to the first ball screw shaft 30. That is, the first ball screw nut 32 may include an inner periphery having a female threaded part corresponding to a male threaded part formed on an outer periphery of the first ball screw shaft 30.
Similar to the first ball screw shaft 30, the second ball screw shaft 40 also passes through the guide rail support frame 23 and is rotated by the second drive unit 44. The second drive unit 44 is supported by a bracket 54 fixed to the base frame 52 disposed under the second drive unit 44. The second drive unit 44 may be connected to one end of the second ball screw shaft 40 to be rotated by a motor.
A second ball screw nut 42 is installed at a through-hole (not shown) of the guide rail support frame 23a connected to the second ball screw shaft 40. That is, the second ball screw nut 42 may include an inner periphery having a female threaded part corresponding to a male threaded part formed at an outer periphery of the second ball screw shaft 40.
Here, the second ball screw shaft 40 can be rotatably supported by a first support frame 56 and a second support frame 58 via ball bearings (not shown) disposed in the support frames 56 and 58.
The guide blocks 20 are connected to the base frame 52 by a connection bar 70 having a connection piece 72. A reference rail 60 is installed at the base frame 52 to guide movement of the connection bar 70. Specifically, a reference piece 62 formed at the reference rail 60 slidably engages a groove formed in the connection piece 72 so that the guide blocks 20 can move along the reference rail 60.
Hereinafter, position movement of the substrate transfer apparatus 10 will be described.
First, the second ball screw shaft 40 is rotated by the second drive unit 44 while the first drive unit 34 does not operate. The second ball screw shaft 40 engages the second ball screw nut 42 to move the guide blocks 20.
That is, the guide blocks 20 can only horizontally move while maintaining a certain width therebetween.
FIG. 2 illustrates the known substrate transfer apparatus, in which the first ball screw shaft 30 projects outward due to movement and width adjustment of the guide blocks 20. As shown in FIG. 2, it is possible to freely vary the position where the printed circuit board 28 can be supplied through the second drive unit 44.
Meanwhile, variation in size of the printed circuit board 28 requires varying the width W between the guide blocks 20. In this case, the first drive unit 34 operates while the second drive unit 44 stops.
The operation of the first drive unit 34 causes rotation of the first ball screw shaft 30. The first ball screw shaft 30 and the first ball screw nut 32 engage each other to move the second guide block 22, thereby varying the width W between the guide blocks 20.
As described above, the known substrate transfer apparatus 10 can adjust the position of the guide blocks 20 and the width W between the guide blocks 20 using the ball screw shafts 30 and 40, thereby supplying various printed circuit boards 28 having different widths.
A disadvantage of using the plurality of ball screw shafts 30 and 40 in the known substrate transfer apparatus 10 is an increase in manufacturing cost. In addition, referring to portion “A” of FIG. 2, during the process of adjusting the position and the width W of the guide blocks 20, the first ball screw shaft 30 may project beyond the base frame 52 such that a marginal space should be provided in the component mounting device.
An additional disadvantage is that the excessive projection of the first ball screw shaft 30 may cause portion “A” of the shaft 30 to be unsupported, and thus normal operation at the connection part with the guide blocks 20 may not be performed.